On Wed, Mar 12, 2014 at 07:03:14PM -0400, Dave Chinner wrote: > On Wed, Mar 12, 2014 at 08:14:32PM +0000, Mears, Morgan wrote: >> Hi, >> >> Please CC me on any responses; I don't subscribe to this list. >> >> I ran into a possible XFS bug while doing some Oracle benchmarking. My test >> system is running a 3.14.0-rc3+ kernel built from the for-next branch of >> git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git >> on 2014-02-19 (last commit 1342f11e713792e53e4b7aa21167fe9caca81c4a). >> >> The XFS instance in question is 200 GB and should have all default >> parameters (mkfs.xfs /dev/mapper/<my_lun_partition>). It contains Oracle >> binaries and trace files. At the time the issue occurred I had been >> running Oracle with SQL*NET server tracing enabled. The affected XFS >> had filled up 100% with trace files several times; I was periodically >> executing rm -f * in the trace file directory, which would reduce the >> file system occupancy from 100% to 3%. I had an Oracle load generating >> tool running, so new log files were being created with some frequency. >> >> The issue occurred during one of my rm -f * executions; afterwards the >> file system would only produce errors. Here is the traceback: >> >> [1552067.297192] XFS: Internal error XFS_WANT_CORRUPTED_GOTO at line 1602 of file fs/xfs/xfs_alloc.c. Caller 0xffffffffa04c4905 > > So, freeing a range that is already partially free. The problem > appears to be in AG 15, according to the repair output. > >> https://dl.dropboxusercontent.com/u/31522929/xfs-double-free-xfs_metadump-before-repair.gz > > AGF 15 is full: > > xfs_db> agf 15 > xfs_db> p > magicnum = 0x58414746 > versionnum = 1 > seqno = 15 > length = 3276783 > bnoroot = 1 > cntroot = 2 > bnolevel = 1 > cntlevel = 1 > flfirst = 0 > fllast = 3 > flcount = 4 > freeblks = 1 > longest = 1 > btreeblks = 0 > uuid = 00000000-0000-0000-0000-000000000000 > lsn = 0 > crc = 0 > > And the one free block (other than the minimum 4 on teh AGFL) is: > > xfs_db> p > magic = 0x41425442 > level = 0 > numrecs = 1 > leftsib = null > rightsib = null > recs[1] = [startblock,blockcount] 1:[3119876,1] > > But: > > data fork in ino 940862056 claims dup extent, off - 11, start - 58836692, cnt 1 > correcting nextents for inode 940862056 > bad data fork in inode 940862056 > would have cleared inode 940862056 > > the block number here is in AG 14, which has much more free space: > > xfs_db> p > magicnum = 0x58414746 > versionnum = 1 > seqno = 14 > length = 3276783 > bnoroot = 1 > cntroot = 2 > bnolevel = 1 > cntlevel = 1 > flfirst = 42 > fllast = 45 > flcount = 4 > freeblks = 2092022 > longest = 2078090 > btreeblks = 0 > > which is in 2 extents: > > xfs_db> a bnoroot > xfs_db> p > magic = 0x41425442 > level = 0 > numrecs = 2 > leftsib = null > rightsib = null > recs[1-2] = [startblock,blockcount] 1:[102466,13932] 2:[116476,2078090] > xfs_db> convert agno 14 agbno 102466 fsb > 0x3819042 (58822722) > xfs_db> convert agno 14 agbno 116476 fsb > 0x381c6fc (58836732) > > and so 58836692 is just short of the second free space. Looking at > all the other dup extent claims, they a remostly adjacent to the > left edge of these two free spaces. No surprise - that's the way > allocation occurs. > > So, we've got a state where the allocation btree contains a > corruption, so a shutdown occurs. The log has captured that > corruption when it was made, so log recovery reintroduces that > corruption. And so when the extent is freed after log recovery, the > corruption is tripped over again. > > There's two checkpoints in the log, both very small. The last > modification to AGI 14 is there before it: > > BUF: cnt:2 total:2 a:0x669350 len:24 a:0x6693d0 len:128 > BUF: #regs:2 start blkno:0x15dff891 len:1 bmap size:1 flags:0x2800 > AGF Buffer: (XAGF) > ver:1 seq#:14 len:3276783 > root BNO:1 CNT:2 > level BNO:1 CNT:1 > 1st:42 last:45 cnt:4 freeblks:2092020 longest:2078090 > > As is the freespace btree buffer modification: > > BUF: cnt:2 total:2 a:0x669460 len:24 a:0x6694e0 len:128 > BUF: #regs:2 start blkno:0x15dff898 len:8 bmap size:1 flags:0x2000 > BUF DATA > 0 42544241 4000000 ffffffff ffffffff cb620100 1000000 fc7c0100 2000000 > magic = BTBA > level = 0 > numrecs = 4 > leftsib = NULLFSBLOCK > rightsib = NULLFSBLOCK > rec[0] = 0x162cb, 1 (90827,1) > rec[1] = 0x17cfc, 2 (97532,1) > 8 47900100 67360000 fcc60100 8ab51f00 71ff3100 5000000 71ff3100 5000000 > rec[2] = 0x19047, 0x3667 (102471,13927) > rec[3] = 0x1c6fc, 0x1fb58a (116476,2078090) > > so, from the pre-recovery case above, we've got two new freespaces > in rec[0-1], rec[2] has 5 blocks removed from the left edge, and > rec[3] is unchanged. > > Confirming the ABTC buffer contains the same extents: > > BUF: cnt:2 total:2 a:0x669570 len:24 a:0x6695f0 len:128 > BUF: #regs:2 start blkno:0x15dff8a0 len:8 bmap size:1 flags:0x2000 > BUF DATA > 0 43544241 4000000 ffffffff ffffffff cb620100 1000000 fc7c0100 2000000 > magic = CTBA > level = 0 > numrecs = 4 > leftsib = NULLFSBLOCK > rightsib = NULLFSBLOCK > rec[0] = 0x162cb, 1 (90827,1) > rec[1] = 0x17cfc, 2 (97532,1) > 8 47900100 67360000 fcc60100 8ab51f00 71ff3100 5000000 71ff3100 5000000 > rec[2] = 0x19047, 0x3667 (102471,13927) > rec[3] = 0x1c6fc, 0x1fb58a (116476,2078090) > 10 8ca0100 8000000 71ff3100 5000000 71ff3100 5000000 71ff3100 5000000 > 18 71ff3100 5000000 71ff3100 5000000 71ff3100 5000000 71ff3100 5000000 > > It does. So the btrees contain consistent information, and so it's > unlikely that we have a free space btree corruption in the log. So > let's look at what was freed: > > The EFI/EFDs in the log are: > > EFI: cnt:1 total:1 a:0x668670 len:32 > EFI: #regs:1 num_extents:1 id:0xffff881496024af0 > (s: 0x38162cb, l: 1) > EFD: cnt:1 total:1 a:0x6684d0 len:32 > EFD: #regs: 1 num_extents: 1 id: 0xffff881496024af0 > .... > EFI: cnt:1 total:1 a:0x667da0 len:32 > EFI: #regs:1 num_extents:1 id:0xffff8814960244b0 > (s: 0x3817cfc, l: 1) > EFD: cnt:1 total:1 a:0x65fbd0 len:32 > EFD: #regs: 1 num_extents: 1 id: 0xffff8814960244b0 > .... > EFI: cnt:1 total:1 a:0x669250 len:32 > EFI: #regs:1 num_extents:1 id:0xffff881496024000 > (s: 0x3817cfd, l: 1) > EFD: cnt:1 total:1 a:0x6692d0 len:32 > EFD: #regs: 1 num_extents: 1 id: 0xffff881496024000 > > These are all in ag#14, and have agbnos of 0x162cb, 0x17cfc and > 0x17cfd. This corresponds exactly to the two new records in the AG > btree. The one remaining EFI doesn't have an EFD in th elog, so this > is what is being replayed: > > EFI: cnt:1 total:1 a:0x669f40 len:32 > EFI: #regs:1 num_extents:1 id:0xffff881496024640 > (s: 0x3869ff9, l: 1) > > Which is at agbno 0x69ff9 (434169). That's off to the right of the > start of the last freespace range in rec[3]. rec[3] starts at > 0x1c6fc and ends at 0x1fb58a. That means this efi clearly lands > inside that freespace range - it's not an edge case, it's deep in > the interior of the freespace range. > > The inode logged just before the EFI - likely it's owner: > > INO: cnt:2 total:2 a:0x668040 len:56 a:0x667fb0 len:96 > INODE: #regs:2 ino:0x3862d698 flags:0x1 dsize:0 > CORE inode: > magic:IN mode:0x81b0 ver:2 format:2 onlink:0 > uid:1001 gid:1001 nlink:0 projid:0 > atime:1394495104 mtime:1394495104 ctime:1394554526 > flushiter:1 > size:0x0 nblks:0x0 exsize:0 nextents:0 anextents:0 > forkoff:13 dmevmask:0x0 dmstate:0 flags:0x0 gen:-121998876 > > Is an unlinked inode that has had all it's block removed. Yup - it's > on the unlinked list: > > agi unlinked bucket 24 is 6477464 in ag 14 (inode=946001560) > > So, prior to recovery, what did it contain? it's got 287 bytes of > date, and a single extent: > > u.bmx[0] = [startoff,startblock,blockcount,extentflag] 0:[0,59154425,1,0] > > xfs_db> convert fsb 59154425 agno > 0xe (14) > xfs_db> convert fsb 59154425 agbno > 0x69ff9 (434169) > > Ok, so the corruption, whatever it was, happened a long time ago, > and it's only when removing the file that it was tripped over. > There's nothing more I can really get from this - the root cause of > the corruption is long gone. > > Cheers, > > Dave. > -- > Dave Chinner > david@xxxxxxxxxxxxx Thanks Dave. Upon restarting my testing I immediately hit this error again (or a very similar one in any case). I suspect that the corruption you've noted was not properly repaired by xfs_repair. I captured all the same data as before, as well as an xfs_metadump from after the xfs_repair. If you're interested, it's all in this tarball: https://dl.dropboxusercontent.com/u/31522929/xfs-unlink-internal-error-2013-03-13-1.tar.gz Regards, Morgan _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
